/*
 * Copyright 2007 Matt Jensen
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package org.jtell.internal;

import org.jtell.config.OrderMetadata;
import org.jtell.config.annotation.Event;
import org.jtell.EventSink;

import java.util.Collections;
import java.util.Set;
import java.util.Map;

/**
 * <p>
 * <code>Empties</code> provides some widely useful stock <em>empty</em> objects.
 * </p>
 */
public class Empties
{
    /**
     * <p>
     * Construct a {@link Empties} instance.
     * </p>
     */
    private Empties()
    {
        super();
    }

    public static final Event EMPTY_EVENT = null;

    /**
     * <p>
     * Stock empty attribute map.
     * </p>
     */
    public static final Map<String, String> EMPTY_ATTRIBUTES = Collections.emptyMap();
    
    /**
     * <p>
     * Stock empty contribution set.
     * </p>
     */
    public static final Set<String> EMPTY_CONTRIBUTIONS = Collections.emptySet();

    /**
     * <p>
     * Stock empty order set.
     * </p>
     */
    public static final Set<OrderMetadata> EMPTY_ORDER_METADATAS = Collections.emptySet();

    /**
     * <p>
     * Stock empty event sink set.
     * </p>
     */
    public static final Set<EventSink> EMPTY_EVENT_SINKS = Collections.emptySet();
}
